Printed wiring boards have pads thereon which are coated with solder. Electrical components are positioned so their electrical leads lie on the pads. The solder is heated to melting so that the leads are connected to the pads by means of a solder joint. There are a number of ways for heating the solder. One of the ways is to apply a heater bar to the lead, for heating the lead and solder. An example of this is Joseph M. Jacos and Robert F. Hubbard U.S. Pat. No. 4,654,507 entitled "Solder Reflow Heater Bar Assembly." The structure described in that patent is eminently successful.
The present trend in the technology where components are mounted on the surface of the printed wiring board is toward closer spacing between the components. As a result, it is difficult to gain access to the leads to apply heat to the leads in these closely spaced structures. In addition, the surface of the printed wiring board may not be absolutely level, and rocking of the heater bar assembly is necessary to accommodate for this out-of-level configuration. Rocking of the heater bar around a high pivot point causes lateral displacement of the leads. When the pads are smaller, due to attempts to increase the number of components in the printed wiring board, the lateral shifting due to rocking of the heater bar may move a lead off of its pad. Thus, a compact structure which minimizes lateral shifting upon rocking is required in order to meet the close spacing of components and small pads found on modern printed wiring boards.